Combined transmitting and receiving arrangement



0a. 13, 1925. 1,557,067 L. KUHN COMBINED TRANSMITTING AND RECEIVING ARRANGEMENT Filed Aug. 26, 1921 Patented Oct. 13, 192 5.,

. .UNITED STATES Parent LUDWIG Kfimr, or nnanm-cnannorrmuae,

nousn mmcrmc a am .comnmnn 'rnansm'r'rme AND. nncmvme ARRANGEMENT.

A 1,557,061, FFlC-E.

GER-WY, assrenon r0 wrsrmm KAI Z'UFACTUBING OOIIPAIYQA CORPORATION '01 PENNSYL- a Application filed Augult. as, 1921: Serial Romance.

T 0 all whom it may concern:

Be it known that I, Lunwre KfiHN, a subject of the Republic of Germany, residin at 103 Kaiser-Friedrichstrasse, Berlin-Char 0t tenburg, Germany, have invented certain new and useful Im rovements in Combined Transmitting and eceiving Arrangement for which applicant has filed in the followmg countries-Germany, December 14, t1T917 uly I and December 15, 1917; Great Britain,

' 12, 1920; France, July 30, 1920; Denmark, April 16, 1920.; Holland, March 5, 1920;. Sweden, January 3, 1920), of. which the following is a specification.

The present invention relates nailing systems and has for its object the provision of a system .employing vacuum tubes, which is particularly adapted for re-- Referrin now to the drawing, an antenna 6 is coupled tube 1 by means of the variable. inductance 5, a, portion of which is common to both the plate circuit of the vacuum tube 1 and the antenna circuit. The antenna circuit may be conveniently tuned by means of the variable inductance 5 or the variable induce tance 7 which'is included in the antennacir- 4 cuit although any other commonly employed tuning arrangement may be utilized. Inasmuch as in the embodiment shown, the conto the plate circuitof a vacuum pling between the plate circuit of the tube 1- and the antenna circuit is varied by relative adjustments of the amount. of inductance 5 in each of the circuits,the variable inductance 7 is convenient in tuning the antenna circuit.

The plate circuit of tube 1 includes besides the variable inductance 5, the primary 10 'of a transformer 11 and a battery 8 or other source of potential. It is desired that the battery and the transformer primary be j shunted by condensers 9 and 12 respectively cluded in t and the ap lied potential of the battery be made varia le by means such as a switch 13. a The id circuit of'the tube 1 may be also tune to any desired frequency by means of the variable condenser 18 which is in paral-' lel with the inductance 17. A condenser 19 in this circuit is shunted by the secondary of a transformer 21, the leads to which are ar ranged so theymay be disconnected at any convenient points such as 37. In order to control the grid bias potential the grid circuit is connected to the filament by a lead 16 contacting with a resistance element 15 in v the filament circuit. This resistance element to wave sigalso serves to control the current from the battery-.14 throughthe filament 4. p

The plate circuit of a second vacuum tube 22 includes the primary of the transformer"? '21 and is thus coupled to the grid'circuit of tube 1. The primary 23 of another transformer 24 is in the plate circuit of tube 22 and" switching means are also included whereby the circuit may be interrupted at any convenient points as 'at 36.

As shown,'the plate potential of the tube 22'gnay be obtainedfrom the battery 8 and the filament current from the battery 14, .a resistor 29, refera'bly of iron wire, being ine filament, circuit to limit the current. a I 1 I A third vacuum tube 32 may be provided, the plate circuit of which includes the mdicating device 35, and the battery 8, and the grid circuit of whichv includes the seconds. of the transformer 24 and is thereby coupled to the plate circuit of tube 22. The filament 9 33 of tube 32 may be connected as shown so as to be heated from the battery 14, a resistor 34 being in circuit to limit the current.

- As illustrated, the connections are ar-. ranged for the reception of continuous wave signals by the heterodyne method. The gridland late circuits of tube 1 may be tuned so that the tube 1 will oscillate. at a frequencyslightly diflerent from the frequency-of thesignal to be received. The 100.

continuous waves received by tlieantenna system will then combine with the continuous waves produced by the local oscillator, j resulting in the .well known beat note of audible frequency. The oscillations of beat note frequency are conducted through the transformer 11 to thegrid of the vacuum tube 22, which produces an amplified oscillation in its plate circuit. To obtain a feedback action, this plate circuit iscoupled by transformer 21 to the id circuit of tube 1 so'that the tube 1 wi act as an amplifier transferring the energy again from its plate circuit to t e grid circuit of tube 22. The plate circuit of tube 22 also contains the primary of transformer 24, the secondary of which is in the grid circuit of tube 32. This tube further amplifies the signals which are received by the indicating device, preferably a telephone, 35, which is in the plate circuit of this tube.

By changing a few connections of this receiving circuit, the apparatus may be 7 adapted for use as a transmitter of either continuous waves, modulated continuous waves or speech. i

For the transmission of continuous wave signals, the transformer 21 is cut out of circuit by either bridging across it or opening the leads at 37 by means of a switch. It is advisable to positively render the tube 22 inoperative by opening its plate circuit at 36.

With these changes the plate and grid circuits of tube 1 and the antenna circuit may be adjusted to the desired transmitting frequency and the energy for radiation will be supplied thereto, as will be readily understood by those skilled in the art. In order to interrupt the transmission in accordance with the signals to be sent out a key may be rovided in the antenna circuit so as to interrupt the circuit or a key in parallel with an inductance may be coupled to any of the circuits to changethe frequency of that circuit thus controlling the oscillation of the tube. These methods form no part of this invention and are so well known that it is unnecessary to illustrate them.

If modulated continuous ,waves are to be transmitted the inductance 20 is included in the grid circuit of tube 1 by closing the switches 37, so that an oscillating circuit of audible frequency is formed by the inductance 20 and condenser 19. As is well known these audible frequency oscillations will be impressed 'on the super-audible frequency oscillations in the oscillating grid circuit so as to modulate them at an audible frequency. The audible frequenc oscillations will be changed in frequency y variations in either condenser 19 or inductance 20 and it is preferred that the inductance 20be made variable. I

The superaudible frequency /or carrier wave oscillations may be varied in frequency in the'usual manner by adjustments ofcondenser 18 and corresponding adjustments of plate and antenna circuits.

In order to transmit speech, a microphone 38 and battery 39 may be coupled to the grid circuit of tube 1, preferably by means by connecting leads 40 and 41 across the transformer primary I as indicated on' the quency oscillations in the system it has been found desirable to have all the transformers of the same ratio and to connect them in circuit so that the current flows in the same direction through the primary and secondary. The adjustable slider 16 may be varied to control the grid bias potential to stabilize the system for prevention of undesirable oscillations.

In transmission best results are obtained with a particular coupling between the plate circuit of tube 1 and antenna 6. This coupling may be varied by independently adjusting the amount of inductance 5 in each circuit and the antenna system may be tuned with variable inductance 7. Inasmuch as the coupling is not as important during reception as during transmission, and is usually about the same in both cases, it is not necessary to change the coupling for reception and it ma be left at the value which is found to be est for transmission.

In order to further simplify the operation of the apparatus the controls for the antenna circuit and grid circuit may be mechanically connected so that changes in the circuits are made simultaneously by manipulation of 'to at all limit the spirit or scope of this invention as various modifications will be apparent to those skilled in the art.

I claim:

1. In a radio communication system, an antenna, a vacuum tube, circuits associated with said tube .to cause it to function as both an oscillator and a detector, said associated circuits including a coupling to the antenna, a grid circuit and a circuit coupled to the antenna and to the grid circuit, an amplifier in said coupled circuit, an indicating device associated with said coupled circuit, and switching means for opening said coupled circuit, whereby. when said coupled circuit is closed, signals ma be received by heterodyne reception and w en said switching means are open, said vacuum tube may function as a transmitter of continuous waves. I

2. In a radio communication system, an antenna, a vacuum tube, circuits associated with said tube to cause it to function as both an oscillator and .a detector, said associated circuits including a plate circuit coupled to quency oscillating the antenna, a grid circuit, an audio-frecircuit-in said 'd circuit, and a circuit coupled to the antenna and to the grid circuit-an indicating device associated with said coupled circuit, and

switching means for opening said coupled circuit, whereby when said cou led circuit is closed, signals may be receiv by heterodyne reception and when said switching means are open, said vacuum tube may function as a transmitter of modulated continuous waves and switching devi for render- 7 ing inoperative said audio-fr uency oscillating circuit whereby said transmitter may 7 be caused to deliver unmodulated waves.

to the plate circuit of said oscillator and del tector ,tube whereby received continuous waves are impressed upon the oscillator-and detector tube for heterod 0 reception, an amplifying tube circuit, including indicating-means, coupled to said tube repeater circuit, switching means for-disconnecting said repeater circuit and associated indicating a device whereby said oscillator tube is rendered operative asatransmitter of modulated coutinuouswaves and switching means for Y uum t'irbe oscillator and detector com rising I a grid circuit which includes an au '0 frequency oscillating circuit and a plate circuit coupled to said antenna, a vacuum tube repeater comprising a plate circuit coupled to the grid circuit of said oscillator and dey tector tube and a grid circuit coupled to the plate circuit of said oscillator anddetector tube whereby receivedcontinuous waves are impressed upon the oscillator anddetector tube for heterod' ne reception, an amplifying circuit, inc uding indicat'i means, coupled to said tube repeater circuit, switch ing means for disconnectin said repeater circuit and associated indicating device whereby said oscillator tube is rendered operative as a transmitter of modulated continuous waves, switching means for cutting out said audio frequency oscillating circuit from the grid circuit of said oscillator tube to render said oscillator operative as a transmitter of continuous waves and switching means for co said micro bone to said oscillator to ren er said osei ator operative as a continuous wave Y telephone transmitter. I

In testimony whereofl afiix my si ture.

' DR. me. ;LUDWIG. 

